In medical and nursing care facilities, accidents such as wandering and a fall can occur when a patient leaves his/her bed without being noticed by caregivers. To suppress the occurrence of such accidents, a technique for detecting a motion related to the leaving of a patient from a bed, such as standing up, has been proposed.
For example, a camera for capturing a head of a patient or the like is installed above the head side of the bed, like directly above the headboard. The bed leaving of the patient or the like is detected depending on whether the position of the head detected from an image captured by the camera exceeds lines that are set with reference to both sides of the bed.
Patent document 1: Japanese Laid-open Patent Publication No. 2012-170483
Patent document 2: Japanese Laid-open Patent Publication No. 2013-149205
Since a camera installed above the head side of the bed may interfere with treatment or caregiving, a camera is not always able to be installed above the head side of the bed. If a camera is installed in an oblique direction to the bed and the lines for determining the leaving from the bed are set with reference to both sides of the bed, the lines to be used to determine the bed leaving may be set in an area where the bed appears in the image captured by the camera. In such a case, the head can pass the lines due to a motion made on the bed other than standing up, like a roll-over and a motion in a sitting position. This causes false detection of the bed leaving.